The invention relates to an amplifier comprising an amplifier stage having an input terminal for receiving an input signal; an output terminal for supplying an output signal in response to the input signal; a supply terminal; an amplifier transistor having a main current path coupled to the output terminal; and a load coupled between the output terminal and the supply terminal.
Such an amplifier is known from the general state of the art. The load in such an amplifier takes the form of a diode, which is generally constructed as a diode-connected transistor. The voltage gain of the amplifier stage is then determined by the ratio between the transconductances of the amplifier transistor and the diode-connected transistor.
A disadvantage of the known amplifier stage is that the voltage on the output terminal cannot approximate to the voltage on the supply terminal owing to the threshold voltage of the diode. For certain uses it is necessary that the voltage on the output terminal approximates to the voltage on the supply terminal.